AVS 47th International Symposium
    Surface Engineering Tuesday Sessions
       Session SE-TuM

Paper SE-TuM3
Stress Evolution in TiN and TaN Layers and Multilayers Prepared by Reactive Magnetron Sputtering and Studied with in-situ Laser Reflection Curvature Technique

Tuesday, October 3, 2000, 9:00 am, Room 201

Session: Interface Engineering and Graded Films: Structure and Characterization
Presenter: T. Joelsson, IFM Linköping University, Sweden
Authors: T. Joelsson, IFM Linköping University, Sweden
J. Birch, IFM Linköping University, Sweden
P. Sandström, IFM Linköping University, Sweden
L. Hultman, IFM Linköping University, Sweden
Correspondent: Click to Email
TiN and TaN are interesting materials for an industrial purpose both as hard coatings and as contact materials and diffusion barriers in microelectronics. Control and understanding of the stress evolution in these films is of importance since problems such as delamination and cracking may occur due to compressive and tensile stresses. We have used time-resolved in-situ curvature technique to measure the stress evolution during UHV magnetron reactive sputter deposition onto Si wafers. 800 nm thick individual layers of TaN and TiN have been studied at different nitrogen partial pressures during growth. For TaN at low nitrogen partial pressures, the stress evolution is first tensile with a maximum level of around 0.5 GPa then after 30 nm it turns compressive. At higher nitrogen partial pressures the TaN layers are always compressive. For TiN the layers starts to grow compressive and then turns tensile. For TiN in multilayer and at low nitrogen partial pressure (0.45 mTorr) first a tensile stress is developed then a compressive and finally a tensile stress. This can be correlated with the coalescence stages. The initial compressive state seen in the TiN films is probably correlated to heating of the sample due to bombardment of energetic species (approximately 40° C). When TiN and TaN are deposited sequently to form a multilayered structure the overall residual stress is determined by the thickness of the individual layers and the eventual thermal relaxation time between the different layers. TaN also exhibits phase transformations as a function of layer thickness in a multilayer stack, which in turn offsets the stress evolution.